如何爲每個唯一用戶標識提取兩行

Question

以下查詢用於提取以下列&行。

問題是我不能從每個用戶ID提取兩行。 如果我使用的限制，然後只提取前兩行。

所以我如何可以爲每個唯一用戶ID提取兩行。

例如：

two rows of userid 222 
two rows of userid 122 
two rows of userid 367 

等

TEXT OP：

預期輸出：

Answer 1

假設ID是你的用戶ID和POST_ID是獨一無二的。

(SELECT id,name,post,Image,post 
    FROM users 
    GROUP BY id 
    ORDER BY id 
) 
UNION 
(SELECT id,name,post,Image,post 
    FROM users 
    WHERE post_ID NOT IN 
    (SELECT post_ID 
    FROM users 
    GROUP BY id 
    ORDER BY id) 
    GROUP BY id 
    ORDER BY id 
) 
ORDER BY id, post_ID 

---

請檢查我的查詢從中我得到的答案如下：

(
SELECT store_id, `key_id` , `string` , `translate` , `locale` 
FROM `core_translate` AS C 
GROUP BY `store_id` 
ORDER BY `store_id` 
) 
UNION (

SELECT store_id, `key_id` , `string` , `translate` , `locale` 
FROM `core_translate` AS C 
WHERE `key_id` NOT 
IN (

SELECT `key_id` 
FROM `core_translate` AS C 
GROUP BY `store_id` 
ORDER BY `store_id` 
) 
GROUP BY `store_id` 
ORDER BY C.`store_id` 
) 
ORDER BY store_id, `key_id` 

---

store_id key_id string translate locale 
0 20 Screensize Screensize en_US 
0 21 Gender Gender en_US 
1 1 Size Size en_US 
1 2 Color Color en_US 
2 5 Large Image  Large Image  en_US 
2 6 Medium Image Medium Image en_US 
3 10 Manufacturer Manufacturer en_US 
3 11 Dimensions Dimensions en_US 
4 15 Description  Description  en_US 
4 16 Weight Weight en_US 

Answer 2

不知道這是在MySQL可行的，但你能這樣。 我假設id是用戶ID和post_ID是唯一的。

編輯

嘗試要解決MySQL的限制。

select id,name,post_Imagename_small,Image_title,post_ID from users u1 
where u1.post_ID in (
    select u3.post_ID from (
     select u2.post_ID from users u2 
     where u2.id = u1.id 
     limit 2 
    ) s u3 
) 
order by u1.id 

EDIT 2

中，答案不工作的情況下，here是這類查詢問題的一個良好的閱讀，有很多種解決技術途徑了。